They are berries, and berries are fruit. Yes they are green before they ripen, as are lemons, grapefruit, and a number of other fruit that change color when they are ripe. Yes, some of them do look purple, and as you recall,

Elizabeth Isabelle wrote:blueberries often look blue to me

"Often" - not "always." Now, look at that blueberry in the middle of the picture that you posted. It is primarily blue, with a purple spot on it. It would be counter-definitive to say that it is a purple fruit that is mostly blue.

All blueberries do not have to be blue in order to refute your statement: